…. the study was not a randomized clinical trial of soy consumption. That is, rather than randomly assigning breast-cancer survivors to consume or not consume various amounts of soy, then following those participants to see whether they developed recurrent tumors, the study looked retrospectively at women’s self-determined soy-eating habits.

So far so good.

But then came this next bit:

The randomized clinical trial is the gold standard upon which medical practice is determined, and the only kind of trial that gives scientists confidence that other variables are not confounding their results.

Yeah, that’s … not always true. Not when you’re studying something as complex as the human diet, and a disease that can take many years to develop, like cancer.

When it comes to studying diet, lifestyle and cancer prevention, the randomized clinical trial (RCT) is one tool investigators use, but it can’t – and shouldn’t – be considered the be-all and end-all, the “gold standard” in all situations.

After the jump: The difference between studying cancer treatment and studying cancer prevention.